System for measuring delayed-current effects



Jan. 27, 1931.

H. ,C. SILENT SYSTEM FOR MEASURING DELAYED CURRENT EFFECTS Filed Feb. 20. 1929 6 5 UV] v I Z- 1 TMEIMIIIJ S3 f Z i Pi e6 fienuato;

Ecfiolu'vue j v I E l AMA/1M MM I Sentfiu-rent WWYWWW I u fiA/EMHMfA1mm T o. 3.0 4 R 6 l 5 i INVENTOR ATTORN EY Patented Jan. 27; 1931 r I rHonE-Aun TELEGRAPH .coMreriY, A CORPORATION on NEW YOR I i An objectof my inventionistofprov'ide a new andimproved method and corresponding 1SYSTEM-nou 'iunAsunruc net ngeeanem sauces I fiifipucatidi filed February 20, 1929. Serial 1%. 341,520.

4 apparatus .for n'reasuring echo currents and otheitdelay ed current effects." Another ob- 'ject of-myiinvention is toprovideior deterf mining the varying amplitude of an echo current or other delayed current throughout -theessential t me period in which it occurs Anotherob ect of'my invention'isgto provide for measuring such a current effect atterl'the lapse of'a delinite period of time; These' objects and various obj ects-ot my invention will become apparent on consideration sofa limited number of examples of practice according to the inventionywhich I have chosen-for presentation linj-zthe following specification; It will'be'understood that'this specification relates'principally to these examples of the invention and that'the scopeof'the'invention will be indicatedin the appended claims.

Referring to the'drawings, Figure 1 is a diagram of apparatus that'may beemployed in the practiceot'my invention; Fig. 2 is a curve diagramillustrating :the nature of an echo current and 1ts relation tothe principal current; and Figs. 3, 4a-nd- 5'are frag-mental diagrams illustrating modifications; 7

In the diagram of 1 the parts are indicated and labeled symbolically so that their structuralrelationwill be readily apparent without explanation," and T will proceed at once to describe" the use of 1 the apparatus shown inFigxl in the practice of my invenlVith the key K in its normally open iposi tion,- the adjustable oscillatormarked Use.

the winclin r sends its output through. the amplifier 1. 'to between the points'3 and 4 ofthe hybrid coil H. j

Uponclosure of the'key K and consequent operation ottherelay S the oscillator output circuitis immediately opened; this occurs at the beginning of the time period T in the wave representation for sent current in Fig. 2.1 i

The echo current on the line, whatever 'it may be; producesits inductive effect-in the winding between the points 5 and 'G and is 'a'mplifiedin amplifierQ and goes to the adjustable network marked Attenuator.

, locks itself by a circuit throu the envelope'ot'this echo currentxas represented inFig. 2. Briefly stated,the procedure'consis'ts in waiting for a-period of time T; as. indicated in- Fig. '2', and then measuring the amplitude ofthe echo. current for a brief interval of time'z'. I The duration-ofthepeecho current is determined for'the whole duration of time that is essentially involved.

Normally. the; output from v the attenuator of the normally operated relay S ,;but when the key K was closed and the relay S is operis short-circuited,througlr the front contact ated; this opens at S .the energizing circuit of the relay S Atroucethe adjustable condenser C beginsto chargeihroughtheresistance R so that a definite. period of time elapsesuntil-the relay-S releases. This is the time T whosedura-tion is determined by adjustment ot the capacity of the ,con-- denser C \Vhen, atthe end ot the time period T the relay S releases, this eifectiyely'conuects the output circuit of the attenuator through "the band pass filter BPF to the input of the detec tor Det. The output current from the detector operates the relay 8. which causes the signal lamp I to light'up; also the relay S gh the key K as long as the key K isheld closed) 1 Also, when. the relay S releases, it closesa circuit through the relay S which, in turn, 1

up for relay S The relay S is made adjustably slow acting so that the time interval for which the relay S remains released can be adjusted thereby. Thus thebrief time interval 2' is determined, beginning with the, release of its armature by relay S and ending with" the 're-energization of the relay. S througlrthe closure of its pick-up circuit by the relay S The lockingcircuit fOrS' which at the same time serves as a pick-up circuit for S is colm as long as the-key K is held down,

cloi es a locking circuit, for itself and a pickpleted through the kev'K and remainsgclosed o0 n s, p o p l I riod of time T 1s varied by ad ustmennand accordingly thezvarying amplitude otthe The key K is operated repeatedly, and whilethis is being done, the attenuator is adjusted until the loss therethrougli is so great that theoutput current from the detector Det. is barely'sufiicient to operate the relayfiS and flash thelamp I. Each closure of the lkey fKlshould be for a longer .period than the period of time T. The attenuatoris gives the amplitude of i Next the adjustment 7 changed, and by means of'thec'alibr'atieiis calibrated andits reading at this adjustment t d r i st 'cl'u ing e. brief interval i of the condenser: C is thereon thisgives anew-ralue ganda corre;

sponding reading for tlietimeT, Then the key K is operated again repeatedly while the I, attenuator; is brought to the proper adjusti in - theecho'currenton the line in this case may be mined, corresponding to thenew value of the time-period T.

mentyand from its Calibration :the vaiue of the amplitude of the echo current isdeter- Thus by varying the adj ustmeiit'tor Tover' the whole essential range of time, theampli- 'tude of "the echo current can be'plotted for I his range of time, givingthe envelope of the curve shown on the lower line in Fig, 2.

It will be seen that theduration of the short interval 2 is determined byadjustment ofthe slow action for the relay S5.

* The fore oin se uenceof operations has V D C been with an assumed fizied adjustment oi frequencyfor the oscillator 'Osc. The frequency ofjthis oscillatorean be-adjust'edto various desired values andlthe plot of echo 1 current can beobtained forieach such Value as described'above. The band pass filter BPF is ofadvantage wlienthere isnoise on 1 the-line, because it restricts th'ere'ceivedcurrent to approximately thefrequency ofthe oscillator and thus cuts out substantially all of the noise. When there is no noise this band-pass filter may be omitted.

; The term transducer iseinployed in this specification in its usual "sense-to mean any piece of electrical a'pparatnswith a set of input terminals for apphed electroinotive force and a set ofioutput terminals for delivered current. Thus the hybrid coil H in Fig. 1,

with the aszociated 'echoline and network N,

all constitute a transducer with input terminals 3-,sand output terminals 5, 6. Ina sense looked upon as a: delayed current in this transducer as a' whole, and in general my systern may be employed 'for measuring delayed current efieets in transducers. This aspect of theinv'en'tion is indicated inFigB, where any'tra-nsduc'eris indicated symbolically by the 'bonilyi'ng between thepai-r ofinput terminals 3,4 and 'the pair of output terminals V j' i More particularly, this transducer may con- "sist of a looped circuit as indicated in Fig. 4, and in this case the use of my system serves to measure the transient eflect in this circuit.

fried of time determined by:adjust1nent'of the For some purposes, in the study of transient efi'ects, it may be desirable to send into the transducer, not a sustained current subject to be stopped abruptly, as represented in Fig. 2, but a mere short squirt of tone of definite limited duration-.- For this purpose the relay v S ,.iwill lberreplaced by the combination shown in Fig; 5. That is, theapprratus at the left of th points 3%, 7,.. n -9m Figw l rb u ian r i ce yjthefar para ns glllodifiedin this" Way, it will be' seen that the ,oscillator.circuitisnormally open instead of closed fWhen'thekyK isf' closed, at once the relay S closes-the-oscillator circuit and puts current into the transducer. But after a' pcslowl acting relay S this latter. relay opens the circuit ofthe oscillator; from'thisrpointof time, the operation proceeds the same" as for *Fig. 1 after the point of timeiwhen the p'e- 'riod T begins. On releasing. the key K,"the

ed to'have its action initiated tthereby'and-g after a certain'period Ito connect'the said detectorwith theisaidllossnetwork-v- 1 2'. Apparatustfor measuring la. delayed current efiect through a transducer, c'ons'istingof means to 'apply;a;.'standard current to fthe transducer inpnt,'a man'ualkey to cut off such current; adjustable ti1ne-measuring means whose operation isiiiitiated at such jcu't-ofi, and means actuated thereby after a definite measuredlapse of time/to measure the output 1 currentfrom'th'e transducer; r l

'In combination; a-tr'ansd'ueer, an oscillatorconnected therewith on its input side-, an

adjustable loss network connected therewith on its outputsi'de, :a'detectorvadaptedkto betconnected tosaid network,;a relay, a circuit for said relay, an adjustable delaydevice associated with said circuit, azinaniial' -lgeyto disconnect the oscillator and close the circuit of said relay subject to said delay device, and means actuatedbythe irelay to connect the said detector with the said network.

4. In combination,"a' transducerr, an-oscillater adapted to be connected therewithon its input side, an adjustable loss network con-1 25 'nected therewith on its output side, a'current indicator adaptedto beieonnectedto- 'saidnetwork,'.'two relays S and S :acii'cuitiforsz,

adjustable delay means associated with said ,circuit, a" manual keyto cut o'fi' the oscillat-or iao uo r and to establish a circuit for S subject to delay, means actuated by S toconnect the said indicator with the said network and at the same time to energize S slow-acting means associated with S and means controlled by S to cut off said indicator.

In testimony whereof, I have signed my name to this specification this 13th day of F ebruiry, 1929. i Y HAROLD CJSILENT. 

